1. Field of the Invention
The present invention relates to a method for manufacturing a printing head in which a resin or metal material is used to form ink ejecting nozzles. Specifically, the present invention relates to a method for manufacturing an printing head in which when a flying lead portion of a substrate having ejection energy generating elements is electrically connected to a flexible wiring base material having a flying lead terminal portion, the substrate having the energy generating elements is connected to the electric wiring base material having the flying leads with the flying lead terminal portion slacked.
2. Description of the Related Art
A printing head used in an ink jet printing apparatus is provided with a printing element substrate from which ink droplets are ejected. The printing element substrate has a plurality of energy generating means (for example, heaters) that generate energy required to eject ink through ink ejection orifices, electric wiring such as Al which supplies power to each energy generating element; the energy generating elements and electric wiring are formed by a film forming technique. A plurality of ink channels and ejection orifices corresponding to printing elements are also formed by a photolithography technique.
The printing element substrate connects to an electric wiring base material that applies an electric signal for allowing ink to be ejected to the printing element substrate. The electric wiring base material and printing element substrate are connected together using flying leads connected to the electric wiring base material. In this case, to maintain the connection between the printing element substrate and the electric wiring base material, the flying leads need to be slacked.
The substrate having the energy generating elements and the electric wiring base material are laminated to an ink supply member or an ink supply supplementing member. The electric connection portion and flying lead portion are then fixed using a sealing material or the like. Consequently, heat resulting from these steps thermally expands the ink supply member and ink supply supplementing member to pull the laminated electric wiring base material away from the electric connection portion. At this time, if the flying leads are insufficiently slacked, the electric connection portion or flying lead portion may be loaded and disadvantageously cracked or destroyed.
Such a technique as shown in Japanese Patent Application Laid-open No. 5-218141 (1993) is known as a method for forming a slack shape in the flying lead portion. Japanese Patent Application Laid-open No. 5-218141 (1993) presses an elastomer such as silicone rubber against flying leads (inner leads) of an electric wiring base material (TAB tape) electrically connected to a substrate (semiconductor pellet). The flying lead portion is thus bent and slacked.
Another known method for forming a slack shape in the flying lead uses a male mold and a female mold to pre-form a slack shape in the flying lead portion.
However, the conventional technique presses the elastomer or the like against the flying leads electrically connected to the substrate to mechanically bend the flying leads in crank form. This may heavily load the electric connection portion and locally concentrate stress in the flying leads. In particular, if the pitch and width of the flying leads decrease with increasing density of connection terminals of the substrate, the load on the flying leads and electric connection portion further increases. This may make the flying leads or their connection portions more likely to be destroyed, for example, cracked or cut. Furthermore, if an elastomer or the like is pressed against the flying leads, it must be durable.
On the other hand, if a male mold and a female mold are used to form a slack, molding is usually difficult because of the very small size of the flying leads. Further, continuous operation reduces the lifetime of the molds, thus making reliability likely to be degraded. This requires the molds to be frequently replaced, thus disadvantageously increasing manufacturing costs.